Welcome to the forum!
You need to follow the
SLAM Process. To do that, you need a proper test kit. I suggest the
TF-100 / TFPRO or Taylor K2006C. A proper test kit is needed to get the accurate water chemistry results needed to follow the TFP protocols.
While you are waiting on your test kit, add 5 ppm FC worth of liquid chlorine / plain bleach to your pool each evening with the pump running. This will replenish the FC lost each day to the sun and also inhibit any algae in the water from growing further.
I suggest you read through
Pool Care Basics - Trouble Free Pool and even look at a few of our videos
TFP-TV - Trouble Free Pool